2009년도 제2학기 화 학 2 담당교수: 신국조 Textbook: P. Atkins / L. Jones, Chemical Principles, 4th ed., Freeman (2008) Chapter 15 CHAPTER 15 THE ELEMENTS: THE LAST FOUR MAIN GROUPS GROUP 15/V : THE NITROGEN FAMILY Electronic configuration: ns23np Oxidation states: –3 ~ +5 Different reactivities Stable N2 Burning in air, P Semiconductor, As, Sb Metal, Bi Fig. 15.1 N2(l), Sb, red P, Bi, As 15.1 The Group 15/V Elements ◆ Nitrogen, N o o o m.p.: N2(–196 C) cf. O2(–183 C), Ar(–186 C) Stable triple bond: N≡ N, 944 kJ·mol–1 Bacterial fixation of N2 in nodules on the roots of beans, alfalfa,… Haber-Bosch process Electronegativity: 3.0 – Multiple oxidation states: NH3(–3), HNO3(+5), N3 (azide,–1/3) Fig. 15.2 The pea-plant bacteria. Small atomic radius: π -bond formation from 2p-orbitals, N2O3 ◆ Phosphorus (인,燐), P Large atomic radius Æ π -bond formation from 3p-orbitals Æ single bonds, P4O6 1 2009년도 제2학기 화 학 2 담당교수: 신국조 Textbook: P. Atkins / L. Jones, Chemical Principles, 4th ed., Freeman (2008) Chapter 15 Mineral, apatites, Ca3(PO4)2 ∆ 2 Ca34(PO )2(ss) ++6 SiO2( ) 10 C(s) ⎯⎯→+P4(g) 6 CaSiO3(l) +10 CO(g) White (or Yellow) phosphorus: soft, white, very reactive (burns in air, stored in water), tetrahedral P4 molecules, chemiluminescence (trioxide of phosphorus), 연막탄 Red phosphorus: less reactive, matches, amorphous network (chains of linked P4 tetrahedra) Obtained by heating (240oC) white phosphorus without air (iodine catalyst) Red phosphorus, powder ◆ Arsenic (비소,砒素), As Metalloid GaAs Æ used in lasers in CD players ◆ Antimony, Sb Metalloid Pb/Sb electrodes in lead storage batteries Semiconductors (diodes) ◆ Bismuth, Bi Fig. 15.3 Minerals: Orpiment(웅황,雄黃, As2S3), Stibnite Metal (휘안광,輝安鑛,Sb2S3), Realgar(계관석,鷄冠石,As4S4) Low m.p. (271.5oC) Low melting alloys with Pb, Cd… Æ Activating sprinklers in fire detector 15.2 Compounds with Hydrogen and the Halogens ▶ Ammonia, NH3 Dipole moment: 1.47 D (cf. water: 1.85 D) Poor solvent for strong ionic salts ex. KCl Good solvent for ionic salts with polarizable anions ex. KI Very soluble in water: hydrogen bonds between NH3 and H2O Autoprotolysis: ⎯⎯→ + − 2 NH34(am)←⎯⎯ NH (am) + NH2(am) , + − −33 o Kam =[NH4 ][NH2 ] =1×10 at –35 C Strong Lewis base: 2+ 2+ 2+ Fig. 15.4 Add NH3 to Cu (aq) Cu()aq +⎯4 NH33()aq ⎯→Cu(NH)4()aq 2 2009년도 제2학기 화 학 2 담당교수: 신국조 Textbook: P. Atkins / L. Jones, Chemical Principles, 4th ed., Freeman (2008) Chapter 15 ▶ Ammonimum salts Used as fertilizers Decomposition: ∆ (NH42)CO3(sg)⎯⎯→+2 NH3() CO2()g+H2O()g Oxidation: 250o C NH43NO(sg)⎯⎯⎯→+NO2( ) 2 HO2(g) < 300o C 2 NH43NO (sg) ⎯⎯⎯⎯→+2 N2( ) O2(g) +4 H2O(g) Å explosive (dynamite) ▶ Hydrazine, N2H4 Oily, colorless liquid Used as a rocket fuel Obtained by slow oxidation by hypochlorite: −−aqueous alkali 2 NH32(aq) + ClO (aq) ⎯⎯⎯⎯⎯→+N H4(aq) Cl (aq) +H2O(l) Removing corrosive oxygen from water in high T & P steam furnace NH24(aq)+⎯O(2g) ⎯→+N2(g) 2 H2O(l) ▶ Nitrogen halides, +3 oxidation state NF3 (most stable), NCl3 (reacts with water), NI3·NH3 (explosive) 3– ▶ Nitrides, N ∆ 3 Mg()sg+⎯N23( ) ⎯→ MgN2(s) Mg32N (sl) +⎯6 H2O( ) ⎯→+3 Mg(OH)2(s) 2 NH3(g) Fig. 15.5 Magnesium nitride, Mg3N2 – ▶ Azides, N3 175o C N22O(gl) +⎯2 NaNH ( ) ⎯⎯→+NaN3(s) NaOH(l) +NH3(g) ● NaN3 : shock-sensitive, used in airbags for automobiles 2 NaN32(ss) ⎯⎯→+2 Na( ) 3 N (g) ● Hydrazoic acid, HN3 ⎯⎯→ + − HN32+H O←⎯⎯ H3O +N3, pKa = 4.6 3 2009년도 제2학기 화 학 2 담당교수: 신국조 Textbook: P. Atkins / L. Jones, Chemical Principles, 4th ed., Freeman (2008) Chapter 15 ▶ Phosphine (IUPAC name, Phosphane), PH3 Poison gas Used as fumigants (훈증약, 燻蒸藥) Å pesticides Preparation: 3−−3– 2 P (sl) +⎯6 H23O( ) ⎯→+2 PH (g) 6 OH (aq), ( phosphide ion: P ) ▶ Phosphorus halides ● Phosphorus trichloride, PCl3 Liquid, pesticides, oil additive, flame retardant P42 + 6 Cl ⎯⎯→ 4 PCl3 ● Phosphorus pentachloride, PCl5 Colorless, water-sensitive solid, chlorinating reagent PCl32 + Cl ⎯⎯→ PCl5 Hydrolysis Æ no change in oxidation states: +33+ PCl32(ll)3+⎯ HO() ⎯→H3 PO3(s)3+ HCl(g) +55+ PCl52(ll)+⎯4 H O( ) ⎯→+H3 PO4 (s) 5 HCl(g) 15.3 Nitrogen Oxides and Oxoacids Nitrogen oxides, NOx : “nox” Å air pollutants ▶ Dinitrogen oxide (Nitrous oxide, “laughing gas”), N2O +1 250o C NH43NO(sg)⎯⎯⎯→+NO2( ) 2 HO2(g) Tasteless, unreactive, nontoxic gas Used as an anesthetic, foaming agent for whipped cream 4 2009년도 제2학기 화 학 2 담당교수: 신국조 Textbook: P. Atkins / L. Jones, Chemical Principles, 4th ed., Freeman (2008) Chapter 15 ▶ Nitrogen oxide, NO +2 Colorless gas NO gas from exhausts of planes, cars Æ acid rain Neurotransmitter Æ dilating blood vessels Preparations: 1000o C, Pt 4 NH32(gg) +⎯5 O ( ) ⎯⎯⎯→+4 NO(g) 6 H2O(g) − −+ 2 NO2 (aq) ++2 I (aq) 4 H (aq) ⎯⎯→+2 NO(g) I22(aq) +2 H O(l) Acid rains: 2 NO()gg+⎯O22() ⎯→2 NO()g 3 NO22(gl) +⎯H O( ) ⎯→+2 HNO3(aq) NO(g) ▶ Nitrogen dioxide, NO2 +4 Choking, poisonous brown gas ⎯⎯→ 2 NO2 (brown)←⎯⎯ N24O (colorless) Disproportionation (불균등화 반응): +4 +5 +2 NO2 (gl)+⎯H2O( ) ⎯→+2 HNO3(aq) NO(g) Smog formation ▶ Dinitrogen trioxide, N2O3 +3 Blue gas, anhydride of nitrous acid NO(23gl)+⎯H2O() ⎯→ 2 HNO2(aq) Fig. 15.6 Dinitrogen trioxide, N2O3 −100o C – Deep blue liquid Pale blue solid ▶ Nitrites, NO2 +3 ⎯⎯⎯⎯→ Obtained by reducing nitrates: 350o C KNO32(ss) +⎯Pb( ) ⎯⎯→+KNO (s) PbO(s) Processing meat products: Retarding bacterial growth Forming a pink complex with hemoglobin Æ inhibits oxidation of blood (brown) ▶ Nitric acid, HNO3 +5 Colorless liquid acid, b.p. 85oC Used as fertilizers and explosives Å nitroglycerin (dynamite) > trinitrotoluene (TNT) Preparation: Three-step Ostwald process Step 1: Oxidation of ammonia −3 +2 850oC, 5 atm, Pt/Rh 4 HN3()gg+5 O2 ()⎯⎯⎯⎯⎯⎯→+4NO()g6 H2O()g 5 2009년도 제2학기 화 학 2 담당교수: 신국조 Textbook: P. Atkins / L. Jones, Chemical Principles, 4th ed., Freeman (2008) Chapter 15 Step 2: Oxidation of NO +24+ 2 NO(gg)+⎯O2 ( ) ⎯→2NO2 (g) Step 3: Disproportionation in water +4+5+2 3 N O2 (gl) +⎯H23O( ) ⎯→+2 H N O (aq) N O(g) 15.4 Phosphorus Oxides and Oxoacids ▶ Phosphorous(III) oxide, P4O6 P42(sg, white) +⎯3 O ( ) ⎯→ P4O6(s) Å anhydride of phosphorus acid ▶ Phosphorous acid, H3PO3 P46O(sl)+⎯6 HO2() ⎯→4 HP3O(3aq) Å diprotic acid ! ▶ Phosphorous(V) oxide, P4O10 P42(sg, white) +⎯5 O ( ) ⎯→ P4O10(s) Å drying agent, anhydride of phosphoric acid ▶ Phosphoric acid, H3PO4 P41O0(sl)+⎯6 HO2() ⎯→4 HP3O4(aq) ● Usage of phosphoric acid: Fertilizers, food additives, detergents ▶ Phosphates Ca(PO)()sl+⎯2 HSO() ⎯→+2 CaSO()sCa(HPO)(s) 342 24 4 242 superphosphate ● Condensation reaction (축합반응,縮合反應) : Pyrophosphoric acid (H4P2O7) 6 2009년도 제2학기 화 학 2 담당교수: 신국조 Textbook: P. Atkins / L. Jones, Chemical Principles, 4th ed., Freeman (2008) Chapter 15 ● Polyphosphates ★ ATP (Adenosine triphosphate): Energy source in cells – o ATP + H2O ⎯⎯→ ADP (Adenosine diphosphate) + H2PO4 , ∆=G −30 kJ at pH 7 GROUP 16/VI : THE OXYGEN FAMILY 15.5 The Group 16/VI Elements Electronic configuration: ns24np Chalcogens (ore former), 칼코젠 Etymology(어원,語原): Greek chalkos (ore) + -gen (former); from the occurrence of oxygen and sulfur in many ores cf. Halogen (salt former): Greek halos (salt) 7 2009년도 제2학기 화 학 2 담당교수: 신국조 Textbook: P. Atkins / L. Jones, Chemical Principles, 4th ed., Freeman (2008) Chapter 15 ▶ Oxygen, Most abundant element in Earth’s crust Much more reactive than nitrogen Gas: O2 Colorless, tasteless, odorless gas Pale-blue liquid at -183oC Paramagnetic (two unpaired electrons) Heavily consumed in steel industry Responsible for combustion Used in medicine, welding Fig. 15.7 Pale blue liquid O2. ▶ Ozone, O3 Blue gas with pungent smell o Condenses at -112 C to an explosive blue liquid Prepared by passing electric discharge through O2 Also present in smog: UV NO2 ⎯⎯→ NO + O OO+⎯23⎯→O Presence of ozone in stratosphere vital to lives on Earth Fig. 15.8 Dark blue liquid O3. Fig. 15.9 Elecronegativities. Fig. 15.10 Radii (in pm) of atoms and anions of Group 16/VI elements. ▶ Sulfur Atomic radius: S > O EN & IE: S < O Polarity: S-H < O-H Æ H2S(g), H2O(l) ∆, 200o C Catenation (사슬화 반응) Æ S8 rings ⎯⎯⎯⎯→ long strands of “plastic sulfur” Disulfide link: – S – S – Æ structure of proteins Ores: 8 2009년도 제2학기 화 학 2 담당교수: 신국조 Textbook: P. Atkins / L. Jones, Chemical Principles, 4th ed., Freeman (2008) Chapter 15 Fig. 15.11 Sulfide ores: PbS (galena,방연광,方鉛鑛), HgS (cinnabar,진사,辰沙) FeS2 (pyrite,황철광,黃鐵鑛), ZnS (sphalerite,섬아연광,閃亞鉛鑛) ► Frasch process: Extraction of elemental sulfur in porous limestones in salt domes Steam injection Æ Liquefying sulfur (m.p. 115oC) Æ Pumped out by compressed air ► Claus process: 2 H22S()gg+⎯3 O() ⎯→2 SO2()g+2 H2O(l) o 300 C, Al23O 2 H22S()gg+SO()⎯⎯⎯⎯⎯→+3 S(l) 2 H2O()g ● Elemental sulfur Yellow, tasteless, odorless, insoluble, nonmetallic molecular solid, S8 rings Fig. 15.12 Common crystal forms of sulfur: (a) blocklike stable rhombic form (b) needlelike monoclinic form ● Selenium, Se nonmetal, conductivity increases by exposure to light, used in solar cells ● Tellurium, Te Metalloid, semiconductor, alloys ● Polonium, Po radioactive metalloid, source of α -particles, used in antistatic devices in textile industry Fig. 15.13 Se(nonmetal) & Te(metalloid). 15.6 Compounds with Hydrogen ▶ Water, H2O ★ Drinking water Aerator: removing H2S, oxidizing organic compounds to CO2, adding O2 2+ 3+ 2+ Lime, Ca(OH)2: pH increase, precipitates hydroxides of Mg , Fe , Cu Å softening water Primary settling basin: Addition of coagulants: Fe2(SO4)3 or alum, Al2(SO4)3·18H2O Æ Coagulation (응집,凝集) and flocculation (엉김) of precipitates 9 2009년도 제2학기 화 학 2 담당교수: 신국조 Textbook: P.